Rittal TopTherm inverter chiller – improved precision & efficiency

With the focus on flexibility, operation and security Rittal’s complete range of Top Therm chillers now has a reduced depth of 605mm, increasing the number of enclosures to which it may be bayed. The condenser fan, relocated to the roof of the unit, provides an optimised thermodynamic performance and an incorporated condenser protection grill minimises the risk of damage during transit and installation.

The temperature of the chilled water supplied for enclosure cooling is not as critical as that used in process cooling. Spindle cooling demands the cooling medium is supplied within a tolerance of ± 0.5 K, to guarantee the necessary accuracy in processing, otherwise the thermal expansion of the components will cause inaccuracies in the machined workpiece.

Chillers are generally governed by a two-point control system, i.e. turning the compressor on and off as the temperature of the cooling water either rises above or falls below the maximum and minimum permissible limits. However, it is not possible to control within the small hysteresis required for machine cooling using this method as the frequent switching would adversely affect component life.

Rittal’s new TopTherm Inverter Chiller incorporates a variable speed compressor powered by a brushless DC motor, the speed of which is controlled by an inverter, to deliver the cooling medium at a temperature with the required accuracy. This technology, in conjunction with other optimised components in the refrigerant circuit, an electronically controlled expansion valve and energy efficient electronically commutated (EC) fans, has culminated in a range of chillers with a capacity range of 2-19.5 kW, a chilled water temperature tolerance as low as ± 0.2 K and an impressively high energy efficiency ratio (EER) of up to 3.3.